xamarin/Xamarin.Forms

[iOS] CollectionView Image flickers when application is brought back to the foreground

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#7,127 opened on Aug 12, 2019

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a/collectionviewhelp wantedp/iOS 🍎t/bug :bug:up-for-grabs

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Description

Steps to Reproduce

  1. Run the repro by deploying the application to a physical device (I used XS)
  2. Background the app by going to the Home screen
  3. Wait a few seconds
  4. Foreground the app
  5. Notice that there is some flickering below the third image
  6. If unable to reproduce, please try the above steps a few times.

Note that this issue seems to be specific to the 3rd image. If you change its position in the list, then the flickering will continue to happen below that image. That said, I'm not sure if this is an issue with the image renderer or that of CollectionView.

Expected Behavior

There shouldn't be visible UI changes when the application is running in the foreground.

Basic Information

  • Version with issue: 4.3.0.1032-nightly
  • IDE: VS2019

Reproduction Link

App144.zip

Contributor guide

Research direction
Investigate why the flickering occurs specifically for the third image when the app is foregrounded. Focus on CollectionView's cell reuse and image caching mechanisms. Check if the issue is related to image renderer or CollectionView layout.
Tech stack
csharp
Domain
mobile
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
Xamarin.Forms basicsiOS debugging
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
70